Hi, try this on psql console: explain analyze select tq1.*, tq2.* from cal_quat_1 tq1, cal_quat_2 tq2 where tq1.timestamp = tq2.timestamp and tq1.timestamp > '2004-01-12 09:47:56.0000 +0'::timestamp with time zone and tq1.timestamp < '2004-01-12 09:50:44.7187 +0'::timestamp with time zone order by tq1.timestamp; ... and examine generated query plan (or post it) regards, pajout P.S. And what about vacuum full analyze ? :)
Randall Skelton wrote:
Greetings all,
I am trying to do what should be a simple join but the tables are large and it is taking a long, long time. I have the feeling that I have stuffed up something in the syntax.
Here is what I have:
telemetry=> select (tq1.timestamp = tq2.timestamp) as timestamp, tq1.value as q1, tq2.value as q2 from cal_quat_1 tq1 inner join cal_quat_2 as tq2 using (timestamp) where timestamp > '2004-01-12 09:47:56.0000 +0' and timestamp < '2004-01-12 09:50:44.7187 +0' order by timestamp;
telemetry=> \d cal_quat_1 Table "cal_quat_1" Column | Type | Modifiers -----------+--------------------------+----------- timestamp | timestamp with time zone | value | double precision |
telemetry=> \d cal_quat_2 Table "cal_quat_2" Column | Type | Modifiers -----------+--------------------------+----------- timestamp | timestamp with time zone | value | double precision |
My understanding of an inner join is that the query above will restrict to finding tq1.timestamp, tq1.value and then move onto t12.value to search the subset. I have tried this with and without the '=' sign and it isn't clear if it is making any difference at all (the timestamps are identical in the range of interest). I have not allowed the query to finish as it seems to take more than 10 minutes. Both timestamps are indexed and I expect about 150 rows to be returned. At the end of the day, I have four identical tables of quaternions (timestamp, value) and I need to extract them all for a range of timestamps.
Cheers, Randall
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